In: Acta Informatica, Vol. 26, pages 503-525. 1989.
Abstract: The rational index of a non-empty language is a function of N+ into N. The authors prove that the languages associated to Vector Addition Systems or Petri nets have rational indexes bounded by polynomials. An upper bound and a lower bound on the rational index of each term of an infinite sequence of V.A.S. languages is given, such that any V.A.S. language can be obtained as the image by a rational transduction of one of these languages.